soum.sh:
-a option have a effect only on Liger. It give a way to fixe --account argument required
by liger administrators.
-ntask is an experimental option that bypass -nmpi option. It as been tested in the
context of using n nodes (-nnodes n) in exclusive (-exclu) with m mpi task (-ntask m)
with m<n*24 and m/n not an integer.
In this context everything is under control  of slurm (use of srun) thanks to setting of
I_MPI_PMI_LIBRARY env variable mandatory for intel mpi which is for now the default
 for soum.sh on Liger.

LocalConfig_Liger.cmake:
Add openmp in machine dependant stuff as mumps version compiled in
/home/asalzman/develop/ExternalLib/lib use openmp